1. Field of the Invention
This invention relates to the use of terminally blocked fatty alcohol polyethylene glycol ethers as cocollectors with cationic and/or ampholytic surfactants in the flotation of non-sulfidic ores.
Flotation is a separation technique commonly used in the dressing of mineral crude ores for separating valuable minerals from the gangue. Non-sulfidic minerals in the context of the present invention include, for example, apatite, fluorite, scheelite, baryta, iron oxides and other metal oxides, for example the oxides of titanium and zirconium, and also certain silicates and aluminosilicates. In dressing processes based on flotation, the ore is normally first subjected to preliminary size-reduction, dry-ground, but preferably wet-ground and suspended in water. Collectors are then normally added, often in conjunction with frothers and, optionally, other auxiliary reagents such as regulators, depressors (deactivators) and/or activators, in order to facilitate separation of the valuable materials from the unwanted gangue constituents of the ore in the subsequent flotation process. These reagents are normally allowed to act on the finely ground ore for a certain time (conditioning) before air is blown into the suspension (flotation) to produce a froth at its surface. The collector hydrophobicizes the surface of the minerals so that they adhere to the gas bubbles formed during the activation step. The mineral constituents are selectively hydrophobicized so that the unwanted constituents of the ore do not adhere to the gas bubbles. The mineral-containing froth is stripped off and further processed. The object of flotation is to recover the valuable material of the ores in as high a yield as possible while at the same time obtaining a high enrichment level of the valuable mineral.
2. Discussion of Related Art
Surfactants and, in particular, anionic, cationic and ampholytic surfactants are used as collectors in the flotation-based dressing of ores. In contrast to anionic, cationic and ampholytic surfactants, nonionic surfactants are rarely used as collectors in flotation. In Trans. Inst. Met. Min. Sect. C 84 (1975), pages 34 to 39, A. Doren, D. Vargas and J. Goldfarb report on flotation tests on quartz, cassiterite and chrysocolla which were carried out with an adduct of 9 to 10 mol of ethylene oxide with octylphenol as a collector. Combinations of ionic and nonionic surfactants are also occasionally described as collectors in the relevant literature. Thus, A. Doren, A. van Lierde and J. A. de Cuyper report in Dev. Min. Proc. 2 (1979), pages 86 to 109 on flotation tests carried out on cassiterite with a combination of an adduct of 9 to 10 mol of ethylene oxide with octylphenol and an octadecyl sulfosuccinate. In A. M. Gaudin Memorial Volume, edited by M. C. Fuerstenau, AIME, New York, 1976, Vol. 1, pages 597-620, V. M. Lovell describes flotation tests carried out on an apatite with a combination of tall oil fatty acid and nonylphenol tetraglycol ether.
In many cases, the cationic and ampholytic collectors used for flotation do not lead to satisfactory recovery of the valuable minerals when used in economically reasonable quantities.
Accordingly, an object of the present invention is to provide improved collectors which make flotation processes more economical, i.e. with which it is possible to obtain either greater yields of valuable minerals for the same quantities of collector and for the same selectivity or at least the same yields of valuable materials for reduced quantities of collector.